An embodiment of the invention is based on a temperature sensor having the features listed in the claims. Prior art temperature sensors are known from US 6,617,956 B1 and US 7,233,226 B2.
US 6,617,956 B1 and US 7,233,226 B2 disclose temperature sensors comprising a platinum resistor that is arranged on a substrate and covered by a protective ceramic layer of Al2O3. The thin protective layer is covered by a thicker covering layer that is a mixture of Al2O3, MgO and SiO2. The known temperature sensors can only be used at temperatures up to 1000° C. and show significant resistance drift after extended use at such elevated temperatures.
An object of the present invention is to show how the temperature resistance of such sensors can be improved and resistance drift lowered. This problem, and other problems, may be solved by a temperature sensor according to the claims. Further advantageous refinements of the invention may be the matter of the dependent claims.